Basically, a magnetic recording medium is comprised of a non-magnetic support and a magnetic layer containing ferromagnetic powder and is constructed by providing the magnetic layer onto the non-magnetic support. The magnetic layer is generally comprised of ferromagnetic powder dispersed in a binder.
In magnetic recording media having such a construction as mentioned above and particularly in those for VTR use, for example, those having the newly specified 8-mm-width standard, which are narrower in width than the conventional 1/2-inch-width standard, have been put on the market and are getting popularized. Under the above-mentioned circumstances, there have been strong demands for magnetic recording media capable of keeping running durability and performing high density recording operation.
In the meantime, in recent years, there have been the attempts to ferromagnetize magnetic powder and making the powder be fine-grained so that the magnetic recording media may be able to perform high density recording operations.
The ferromagnetization and fine-granulation of such ferromagnetic powder have had the problems. For example, the cohesive action of ferromagnetic powder with each other are enhanced. Therefore, the dispersibility of the ferromagnetic powder is deteriorated so that a high density recording operation may adversely be hindered.
On the other hand, the fine-granulation of ferromagnetic powder will lead to be so inconvenient that, for example, the running durability of magnetic recording media is lowered, such as a scratch on the surface of the magnetic layer of the magnetic recording medium, an edge damage, and so forth.
To solve the above-mentioned inconvenience, there have been attempted to apply the methods of treating ferromagnetic powder in advance with an aluminum compound or a silicon compound, or an aluminum compound and a silicon compound in combination.
However, it can still hardly be said that the magnetic recording media prepared in the above-mentioned methods can fully satisfy the dispersibility of ferromagnetic powder and running durability of magnetic recording medium.
This invention has been devised by taking the above-mentioned circumstances into consideration.